1. Field of the Invention
The present invention relates to an antenna, and in particular to an inverted-F antenna (PIFA) having two different antenna architectures, thus operating at two distinct frequencies.
2. Description of the Prior Art
There is a growing need for dual-frequency antennas for use in wireless communication devices to adapt the devices for dual-frequency operation. For example, the transition of application frequency from 2.45 GHz (IEEE802.11b) to 5.25 GHz (IEEE802.11a) requires an antenna which operates at both frequencies, rather than two single frequency antennas. U.S. Pat. No. 6,252,552 discloses several conventional dual-frequency planar antennas (shown in FIGS. 4-12).
However, each of those conventional dual-frequency planar antennas has a substantially planar structure, which requires relative more mounting surface for installation in an electronic device.
Hence, an improved antenna is desired to overcome the above-mentioned shortcoming of existing antennas.
A primary object, therefore, of the present invention is to provide an inverted-F antenna (PIFA) antenna with two different antenna architectures for operating at two distinct frequencies.
A dual-frequency inverted-F antenna (PIFA) in accordance with the present invention for an electronic device comprises a ground plane, a first radiating patch parallel to the ground plane, a second radiating patch parallel to the first radiating patch, and a first and second connecting portions respectively connecting the first and second radiating patches with the ground plane. A coaxial cable feeder has a conductive inner core wire and a conductive outer shield. The inner core wire is electrically connected to the first radiating patch and the outer shield is electrically connected to the ground plane. The first radiating patch and the ground plane constitute a first frequency resonant structure, and the first and second radiating patches constitute a second frequency resonant structure.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of a preferred embodiment when taken in conjunction with the accompanying drawings.